Process for forming metal images

Abstract

A method for coating a conductive surface with an organic coating where one discrete area of the organic coating is coated onto the surface in an image pattern by conventional means and another discrete area of the organic coating is electrophoretically deposited onto the surface. The process is useful for diverse applications including the fabrication of printed circuit boards.

We claim: 
     
       1. A process for altering a metal surface comprising the steps of electrophoretically applying a first organic photoresist coating over said surface and exposing and developing the same to yield a relief image pattern whereby a part of the surface is coated with said first organic coating and a part of the surface is not coated with said first organic coating, electrophoretically depositing a second organic coating over uncoated areas of the surface, said first and second organic coating being soluble in different solvents, dissolving the first organic coating in a solvent that is not a solvent for the second organic coating, thereby exposing the underlying surface in an image pattern, and permanently altering the exposed underlying surface. 
     
     
       2. The process of claim 1 where the first and second coatings are soluble in aqueous solutions and each coating is insoluble in an aqueous solution in which the other coating is soluble. 
     
     
       3. The process of claim 2 where one coating is soluble in an aqueous acid solution and the other is soluble in an aqueous alkaline solution. 
     
     
       4. The process of claim 2 where the first organic coating is soluble in an aqueous alkaline solution and the second organic coating is soluble in an aqueous acid solution. 
     
     
       5. The process of claim 1 where the substrate is altered by etching. 
     
     
       6. The process of claim 1 where the substrate is altered by a metal plating process. 
     
     
       7. A process for forming a printed circuit board from a circuit board base material having a copper surface comprising the steps of applying a first organic coating over the copper surface of the base material in a relief image pattern whereby a part of the copper surface is coated with said first organic coating and a part of the copper surface is not coated with said first organic coating, electrophoretically depositing copper over the copper surface not coated with the first organic coating, electrophoretically depositing a second organic coating over uncoated areas of the copper surface, said first and second organic coatings being soluble in different solvents, dissolving the first organic coating in a solvent that is not a solvent for the second organic coating thereby exposing the underlying copper in an image pattern, removing the exposed underlying copper and removing the electrophoretically deposited organic coating. 
     
     
       8. The process of claim 7 where the first organic coating is a photoresist that is exposed and developed to yield a relief image. 
     
     
       9. The process of claim 8 where the photoresist is a negatively acting dry film resist. 
     
     
       10. The process of claim 8 where the photoresist is electrophoretically deposited over the conductive substrate. 
     
     
       11. The process of claim 8 where one coating is soluble in an aqueous acid solution and the other is soluble in an aqueous alkaline solution. 
     
     
       12. The process of claim 8 where the first organic coating is soluble in an aqueous alkaline solution and the second organic coating is soluble in an aqueous acid solution. 
     
     
       13. The process of claim 8 where the second organic coating is not photo imageable. 
     
     
       14. The process of claim 8 where the second organic coating is a photoresist.